Method for manufacturing a pipe

ABSTRACT

The present invention relates to a method for manufacturing a pipe, including: a rolling step of arranging a plurality of carbon threads such that the carbon threads tightly contact an outer surface of a mandrel; a heat-molding step of heating the mandrel in a furnace so as to compressively heat the carbon threads such that the latter are molded into a pipe; and a drawing step of removing a compression tape from the molded pipe, and separating the pipe from the mandrel.

TECHNICAL FIELD

The present invention relates to a method for manufacturing a pipe, and more particularly, to a method for manufacturing a pipe, whereby the pipe is light-weight compared to a related art and maintains a maximum strength.

BACKGROUND ART

Pipes are currently used in various fields, such as a fishing rod, a golf club, a badminton racket, a climbing stick, a ski stick, an archery arrow, a bicycle, a tent pole, kayak and canoe paddles, a yacht pole, umbrella ribs, an umbrella pole, a parasol pole, and the like.

These various types of pipes according to the related art are mainly manufactured using a metal material, glass, or a carbon material.

For example, fishing rods according to the related art are mainly manufactured using glass or carbon.

However, fishing rods manufactured using glass have good flexibility and a strong tensile force but are heavyweight. Contrary to this, fishing rods manufactured using a carbon material are light-weight and have a strong repulsive force against elasticity but have a very weak tensile force compared to fishing rods manufactured using glass and have weak shock resistance and thus are easily broken due to small shock.

Since most people who enjoy fishing tend to prefer fishing rods manufactured of a carbon material that is light-weight and has high elasticity to fishing rods manufactured using glass, products that reinforce strength to a fishing rod manufactured using a carbon material by using several methods, have been manufactured.

A method for manufacturing a fishing rod, i.e., a pipe by using a carbon material according to the related art will be described as below.

First, a carbon fabric that is a raw material, is cut to the size of a pipe (a tube of a fishing rod) to be molded, and the cut carbon fabric tightly contacts a mandrel so as to be molded in the form of a pipe. The mandrel in which the carbon fabric tightly contacts in the form of the pipe, is put in a furnace so as to heat-mold the pipe, and the heat-molded pipe is separated from the mandrel, and a cutting process, a combining process, and a painting process of the pipe are undergone such that a desired product can be finally manufactured.

A representative method for reinforcing the strength of a pipe manufactured using the carbon material in this way is as follows. That is, the pipe is manufactured by weaving a Kevlar (which is a trademark name of a product developed by the DuPont company and is almost generalized and known in the field of a bulletproof material) fiber that is a kind of an aramid fiber, is manufactured of terephthalic acid chloride and para-phenylenediamine (PPD), has a very high tensile strength and is mainly used as a bulletproof material, with a carbon fiber so as to heat-mold the woven fiber, or the pipe is manufactured by tightly contacting a Kevlar fabric having a shape of a textile with a carbon fabric so as to heat-mold the fabric, thereby reinforcing the strength of the pipe manufactured using the carbon material by using a high tensile strength of Kevlar.

However, in the method for manufacturing the pipe according to the related art, since the thickness of the Kevlar fiber woven with the carbon fiber or the Kevlar fabric having the shape of the textile that tightly contacts the carbon fabric, which are used to reinforce the strength of the pipe, is very large, for example, each tube of a fishing rod that forms a joint of the fishing rod from a tip to a handle of the fishing rod, is molded very thick, or the carbon fabric is wound around the fishing rod in a state where a cross-section of the carbon fabric is eccentric such that it is difficult to apply the carbon fabric to a process, and when the carbon fabric is wound around the fishing rod in an eccentric state, the eccentric portion and a non-eccentric portion intersect each other, and a load occurs due to the intersecting portion such that the pipe (fishing rod) in one of the eccentric portion and the non-eccentric portion is broken.

In addition, since the Kevlar fabric having the shape of the textile is heavy and is very expensive, the entire strength of the pipe manufactured using the carbon material can be improved; however, light-weight that is the most intrinsic characteristic of the pipe manufactured using the carbon material, cannot be achieved, and cost for manufacturing the pipe increases and causes an economical burden to consumers. Thus, the entire practicality is lowered except for improvement in strength.

Also, according to the related art, when the carbon fabric is wound around fishing rod to be eccentric, a load is concentrated on one side so that the pipe may be easily broken.

DETAILED DESCRIPTION OF THE INVENTION Technical Problem

The present invention provides a method for manufacturing a pipe having an improved structure in which a maximum strength is maintained, light-weight can be achieved and manufacturing cost can be reduced.

The present invention also provides a method for manufacturing a pipe having an improved structure in which carbon threads are used to fundamentally solve a problem relating to eccentricity that occurs when a carbon fabric is wound around the pipe, so that the pipe can be prevented from being broken due to an eccentric load.

Technical Solution

According to an aspect of the present invention, there is provided a method for manufacturing a pipe, the method including: rolling of arranging a plurality of carbon threads to tightly contact an outer surface of a mandrel; taping of arranging a compression tape on an outer surface of the plurality of carbon threads arranged on the mandrel; heat-molding of heating the mandrel in a furnace so as to compressively heat the carbon threads such that the compressively-heated carbon threads are molded into a pipe; and drawing of removing the compression tape from the molded pipe and separating the pipe from the mandrel.

The rolling may include: arranging the plurality of carbon threads in a form of a straight line on an outer circumferential surface of the mandrel in a lengthwise direction from one end to the other end of the mandrel; and winding the carbon threads in a spiral form on the outer surface of the mandrel.

The rolling may include: preparing a mandrel having grooves for forming patterns that are formed on an outer circumferential surface of the mandrel and extend from a lengthwise direction from one end to the other end of the mandrel and arranging a plurality of carbon threads in a form of a straight line so that the grooves for forming patterns of the mandrel are filled with the plurality of carbon threads; and winding the carbon threads in a spiral form so as to cover the straight-line-shaped carbon threads.

An outer diameter of the mandrel may increase gradually from one end to the other end, and the arranging may include: basic arranging of arranging the plurality of carbon threads in a form of a straight line on the outer circumferential surface of the mandrel in a circumferential direction of the mandrel at regular intervals; and additional arranging of arranging a plurality of carbon threads from a point where a gap between the carbon threads arranged in the basic arranging is generated to the other end of the mandrel in a form of a straight line in the circumferential direction of the mandrel at regular intervals, and the additional arranging is performed a plurality of times stepwise up to the other end of the mandrel until the gap between the carbon threads is filled.

The winding of the carbon threads in the spiral form may include winding double-layer carbon threads in a spiral form in each of opposite directions in which the double-layer carbon threads intersect each other.

The method may further include: grinding an outer circumferential surface of the pipe separated from the mandrel; and painting of coating the outer circumferential surface of the ground pipe with a color and waterproof liquid.

Effect of the Invention

In a method for manufacturing a pipe according to the present invention, a carbon fabric like in the related art is not used but carbon threads are used so that a process required when the carbon fabric like in the related art is used (a rolling process of weaving the carbon fabric, cutting the woven fabric according to a mandrel and winding the cut carbon fabric around the mandrel) can be omitted and manufacturing time and manufacturing cost can be reduced due to a simple process.

In addition, a problem relating to an eccentric load that occurs due to an intersecting portion when the carbon fabric is wound around on the pipe according to the relate art, can be fundamentally solved so that a problem relating to a pipe that may be broken due to the eccentric load can be solved.

Thus, the pipe that is light-weight, maintains a predetermined strength and has improved quality with a low price, can be provided.

Furthermore, since the pipe is manufactured by weaving the carbon threads on an outer surface of the mandrel, grooves can be formed on the outer surface of the mandrel in a lengthwise direction of the mandrel, and only part of the carbon threads are arranged on the grooves and then the carbon threads are arranged on the entire portion of the mandrel so that the thickness of every portion of the pipe can be different. Thus, protrusion patterns that extend in the lengthwise direction of the pipe, can be simultaneously formed on an inner surface of the pipe as one body. Thus, the protrusion patterns are formed on the inner surface of the pipe as one body so that rigidity of the pipe can be improved, flexibility (elasticity) thereof can be improved and the reliability of a product can be improved.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram for explaining a method for manufacturing a pipe according to an embodiment of the present invention;

FIG. 2 is a perspective view illustrating a state where carbon threads are wound on an outer surface of a mandrel;

FIGS. 3 through 6 are schematic views for explaining various embodiments in which carbon threads are arranged on the outer surface of the mandrel;

FIG. 7 is a perspective view illustrating a state where the carbon threads are wound around the mandrel and then a compression tape is taped onto the carbon threads;

FIGS. 8 and 9 are views for explaining a method for manufacturing a pipe having a non-circular inner circumferential cross-section by weaving carbon threads on an outer surface of a different type of mandrel; and

FIG. 10 is a cross-sectional view of a pipe having a different cross-sectional shape from that of the pipe illustrated in FIG. 9.

BEST MODE OF THE INVENTION

Hereinafter, a method for manufacturing a pipe according to the present invention will be described in detail by explaining embodiments of the invention with reference to the attached drawings.

Referring to FIG. 1, the method for manufacturing the pipe according to the current embodiment of the present invention includes operations of rolling (S10), taping (S20), heat-molding (S30), drawing (S40), grinding (S50), painting (S60), and product-manufacturing (S70).

First, in the rolling operation (S10), an epoxy resin is coated on the surface of a mandrel 100 that corresponds to a mold, and then, multiple-layer carbon threads 200 (threads for weaving a carbon fabric) including first carbon threads 210 and second carbon threads 220 are arranged, i.e., are wound on an outer circumferential surface of the mandrel 100, as illustrated in FIG. 2.

The mandrel 100 is configured in such a way that an outer diameter of the mandrel 100 increases gradually from one end 110 to the other end 120.

In the rolling operation (S10), the carbon threads 200 may be wound around the mandrel 100 having the above shape by using the following detailed method.

That is, in the rolling operation (S10), the first carbon threads 210 are arranged on the outer circumferential surface of the mandrel 100 from one end 110 to the other end 120 of the mandrel 100 in the form of a straight line, i.e., are basically arranged in a circumferential direction of the mandrel 100 at regular intervals (uniformly), as illustrated in FIG. 3.

In this case, since the mandrel 100 has the outer diameter that increases gradually from one end 110 to the other end 120, the first carbon threads 210 tightly contact one end 110 of the mandrel 100 such that there is no space between the first carbon threads 210 in the circumferential direction of the mandrel 100 and the first carbon threads 210 are basically arranged up to the other end 120 of the mandrel 100 in the form of the straight line. As a result, a gap G is generated between the first carbon threads 210 from a predetermined distance.

Then, another carbon threads 210′ are additionally arranged starting from a point where the gap G is generated, up to the other end 120 of the mandrel 100. In this case, another carbon threads 210′ have a shorter length than that of the carbon threads 210 arranged in the basic arranging operation.

In addition, if it gets close to the other end 120 by a predetermined distance, a gap is also generated between the additionally-arranged another carbon threads 210′ and the basically-arranged first carbon threads 210. Thus, a process of additionally arranging another carbon threads having a shorter length than that of another carbon threads 210′ from the point where the gap is generated and of filling the gap is repeatedly performed stepwise such that the carbon threads 200 can be arranged in the form of the straight line so as to cover the entire outer circumferential surface of the mandrel 100.

Next, in the rolling operation (S10), the first carbon threads 210 are arranged in the form of the straight line, as described above, and then, the second carbon threads 220 are wound on the outer circumferential surface of the mandrel 100, as illustrated in FIG. 4. That is, the second carbon threads 220 are wound on the outer circumferential surface of the mandrel 100 so as to cover the first carbon threads 210 that has been previously arranged on the outer circumferential surface of the mandrel 100 such that multiple-layer carbon threads 200 can be arranged. The thickness of the multiple-layer carbon threads 200, i.e., their stack number is not limited and may be diverse according to a field in which pipes are used, or the size of the pipe.

Here, the field in which pipes are used, may be a fishing rod, a golf club, a badminton racket, a climbing stick, a ski stick, an archery arrow, a bicycle, a tent pole, kayak and canoe paddles, a yacht pole, umbrella ribs, an umbrella pole, a parasol pole, and the like. Pipes may be applied to various fields except for these fields.

That is, in the rolling operation (S10), the thickness of the pipe is determined (adjusted). For example, when a portion having a relatively small thickness, such as a tip of the fishing rod, is molded, single-layer carbon threads 200 can be molded into a form of a tube. When a portion having a relatively large thickness, such as a handle of the fishing rod, is molded, multi-layered carbon threads 200 can be wound around the mandrel 100 and can be molded into a form of a tube, as illustrated in FIGS. 4 and 5.

Also, the second carbon threads 220 to be wound can be wound on an outer surface of the mandrel 100 in a spiral form, as illustrated in FIG. 4, or in a form of a circular band, as illustrated in FIG. 5. In addition, even when the second carbon threads 220 are wound in the spiral form, as illustrated in FIG. 6, double-layer second carbon threads 220 are wound in the spiral form in each of opposite directions in which the double-layer second carbon threads 220 intersect each other, such that the second carbon threads 220 can be in a zigzag form in plane.

In addition, in the current embodiment of the present invention, after the first carbon threads 210 are arranged in the form of the straight line, the second carbon threads 220 are wound on the first carbon threads 210 in the spiral form and are stacked thereon. However, this is just one embodiment, and the order for stacking the first carbon threads 210 and the second carbon threads 220 may be reverse and may be optionally selected.

After the carbon threads 200 are arranged on the mandrel 100, as described above, the taping operation (S20) of winding a compression tape for molding (see 300 of FIG. 6) on an outer surface of the carbon threads 200 is performed. In this case, since an adhesive is attached to a portion where the compression tape 300 contacts the carbon threads 200, the compression tape 300 pressurizes the carbon threads 200 and serves to adhere them each other. In this case, when the carbon threads 200 are thermally treated, a thermal contraction film (compression tape) may be taped onto the carbon threads 200 in a spiral form such that the carbon threads 200 can be more uniformly pressurized.

After the taping operation (S20) is performed, the heat-molding operation (S30) is performed in such a way that the mandrel 100 is heated for a predetermined time (three hours) at the temperature of about 100° C. in a state where the mandrel 100 on which the carbon threads 200 are wound is put in a furnace (not shown), such that the carbon threads 200 can be molded into a pipe by heat and can maintain a predetermined strength and elasticity. A thermo-plastic resin contained in the carbon threads 200 by performing the heat-molding operation (S30), is expanded by heat and is molded with carbon, and the remaining amount of resin solution flows into a gap between the compression tape 300 so that the pipe can be molded.

Meanwhile, the heat-molding temperature and the heat-molding time may be changed in various ways according to the application field of pipes.

Next, after the heat-molding operation (S30) is performed, the drawing operation (S40) is performed. In the drawing operation (S40), the heat-molded pipe is separated from the mandrel 100, and the compression tape 300 is removed from the molded pipe.

Next, in the grinding operation (S50), an outer circumferential surface of the drawn pipe is smoothly ground using a grinding device (not shown). That is, the surface of the pipe that becomes uneven by the adhesive of the compression tape 300 and the resin mold when heat-molding is performed in a state where the compression tape 300 is wound, is smoothly ground.

After the grinding operation (S50) is performed, the painting operation (S60) of forming a painting layer by repeatedly painting the surface of the pipe by using a pigment, a pearl powder, or a sticker as a brush, or by using a spray is performed. In this case, by performing the painting operation (S60), waterproof and strength of the pipe can be improved, and the visual appearance of the pipe can be beautifully implemented by adding color to the pipe. In addition, liquid required for various painting operations can be applied, and the present invention is not limited by a detailed example of the painting operation (S60).

Last, after the painting operation (S60) is performed, the pipe is cut according to sizes and the application fields of pipes, and the cut portions are connected and combined with one another so that a desired product can be finally manufactured (S70). Since the product-manufacturing operation (S70) can be easily understood by one of ordinary skill in the art in view of generally-known technology, detailed descriptions thereof will be omitted.

In the method for manufacturing the pipe described in the current embodiment of the present invention, the pipe having the outer diameter that decreases gradually from one end to the other end, is illustrated. However, this is just one embodiment, and a pipe having a uniform outer diameter from one end to the other end may be manufactured using the same manufacturing method.

In addition, the cross-sectional shape of the pipe may be diverse, such as a circular shape, a non-circular shape, or the like, and the present invention is not limited by the cross-sectional shape of the pipe.

Also, another embodiment of the rolling operation (S10) will now be described with reference to FIGS. 8 and 9. That is, referring to FIG. 8, grooves 101 for forming patterns are formed on an outer circumferential surface of a mandrel 100′ from one end 110 to the other end 120 of the mandrel 100′ along a circumferential direction of the mandrel 100′. Carbon threads 200 including first carbon threads 210 and second carbon threads 220 are arranged on an outer surface of the mandrel 100′ so as to cover the outer surface of the mandrel 100′ having the above structure, thereby manufacturing a pipe. In detail, the first carbon threads 210 are first arranged on the grooves 101 of the mandrel 100′ in a form of a straight line such that the grooves 101 are first filled with the first carbon threads 210. After the grooves 101 are filled with the first carbon threads 210 to have a height (thickness) corresponding to the outermost surface of the mandrel 100′, the second carbon threads 220 are arranged on an outer surface of the first carbon threads 210 in a circular, a spiral, or a zigzag form so as to intersect the first carbon threads 210. Of course, when the first carbon threads 210 are arranged in the form of the straight line, the grooves 101 may be basically filled with the first carbon threads 210, the first carbon threads 210 may be additionally arranged to a predetermined thickness in the form of the straight line so as to cover the entire outer surface of the mandrel 100′ including the grooves 101, and then, the second carbon threads 220 may be finally arranged to intersect the first carbon threads 210. After the rolling operation of arranging the carbon grooves 200 on the outer surface of the mandrel 100′ having the grooves 101 is performed by using the above method, the operations S20, S30, and S40 are performed such that protrusion patterns 403 are formed on an inner surface 401 of a drawn pipe 400 to protrude from a lengthwise direction of the pipe 400, as illustrated in FIG. 9. In this way, the protrusion patterns 403 from the inner surface 401 of the pipe 400 are formed from one end to the other end of the pipe 400 as one body so that rigidity of the pipe 400 can be improved, an elastic force thereof can be improved when the pipe 400 is bent or deformed and the reliability of a product can be improved. That is, since in the related art, a pipe is manufactured using a method of winding a woven fabric directly around a mandrel, it is very difficult to form protrusion patterns for improving rigidity of the pipe on an inner surface of the pipe. However, in the current embodiment of the present invention, when the pipe 400 is manufactured by weaving the carbon threads 200 themselves, the inner surface 401 of the pipe 400 may be formed in various shapes. That is, as illustrated in FIG. 10, a pipe 400′ having an inner surface 405 that is formed in comb-shaped patterns in the lengthwise direction of the pipe 400′, may be manufactured. In addition, the inner surface of the pipe may be formed in various patterns so that rigidity of the finally-manufactured pipe and flexibility (elasticity) thereof can be improved and rigidity of the pipe can be further improved with a smaller thickness than the related art. Thus, light-weight of the product can be achieved and manufacturing cost can be reduced.

The meaning of rolling in the rolling operation in the above-described embodiments of the present invention should be understood to include both a method of winding carbon threads on an outer surface of a mandrel and a method of weaving the carbon threads themselves on the mandrel.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. 

1. A method for manufacturing a pipe, the method comprising: rolling of arranging a plurality of carbon threads to tightly contact an outer surface of a mandrel; taping of arranging a compression tape on an outer surface of the plurality of carbon threads arranged on the mandrel; heat-molding of heating the mandrel in a furnace so as to compressively heat the carbon threads such that the compressively-heated carbon threads are molded into a pipe; and drawing of removing the compression tape from the molded pipe and separating the pipe from the mandrel.
 2. The method of claim 1, wherein the rolling comprises: arranging the plurality of carbon threads in a form of a straight line on an outer circumferential surface of the mandrel in a lengthwise direction from one end to the other end of the mandrel; and winding the carbon threads in a spiral form on the outer surface of the mandrel.
 3. The method of claim 1, wherein the rolling comprises: preparing a mandrel having grooves for forming patterns that are formed on an outer circumferential surface of the mandrel and extend from a lengthwise direction from one end to the other end of the mandrel and arranging a plurality of carbon threads in a form of a straight line so that the grooves for forming patterns of the mandrel are filled with the plurality of carbon threads; and winding the carbon threads in a spiral form so as to cover the straight-line-shaped carbon threads.
 4. The method of claim 2, wherein an outer diameter of the mandrel increases gradually from one end to the other end, and the arranging comprises: basic arranging of arranging the plurality of carbon threads in a form of a straight line on the outer circumferential surface of the mandrel in a circumferential direction of the mandrel at regular intervals; and additional arranging of arranging a plurality of carbon threads from a point where a gap between the carbon threads arranged in the basic arranging is generated to the other end of the mandrel in a form of a straight line in the circumferential direction of the mandrel at regular intervals, and the additional arranging is performed a plurality of times stepwise up to the other end of the mandrel until the gap between the carbon threads is filled.
 5. The method of claim 2, wherein the winding of the carbon threads in the spiral form comprises winding double-layer carbon threads in a spiral form in each of opposite directions in which the double-layer carbon threads intersect each other.
 6. The method of claim 1, further comprising: grinding an outer circumferential surface of the pipe separated from the mandrel; and painting of coating the outer circumferential surface of the ground pipe with a color and waterproof liquid. 